Object Oriented

Objectives

In this part you learn how to write a little game for the game engine which is splitted in many scripts, which are executed every frame.

Instructions

Tasks:

1. Download the .blend file from here
2. Add functions

Preparations

1. Open the the .blend file in Blender
2. Change the Scene layout to »Game Logic«

Running scripts for an object

If you want to run a script for a Blender-Object, you can use the logic bricks to do that. First you have to add an »Always« sensor. Click to the left ‘’‘, for executing the script every frame.

Then add an »Python« controller and set the Script Property to your script.

Then connect them.

The scripts

The script for our Player (The monkey named »Player«).

#! bpy
import bge
import timeit
import aud
import os


def main():
    """Contains all changes"""
    # get scene
    scene = bge.logic.getCurrentScene()
    # get contoller
    con = bge.logic.getCurrentController()
    # get player
    player = con.owner
    # get keyboard
    keyboard = bge.logic.keyboard
    # get the text object
    text = scene.objects["Text"]
    # check if start has already been run
    if "lives" not in player:
        start(player)
    # check for collisions
    for object in scene.objects:
        # does object collide
        # the distance is from origin to origin, so we subtract a bit
        if player.getDistanceTo(object) - 2 <= 0:
            # Is object an enemy ...
            if object.name.startswith("Enemy"):
                if player["can_collide"]:
                    player["lives"] -= 1
                    # play enemy hit sound
                    aud.device().play(player["enemy_sound"])
                    # Set that player can't collide
                    player["can_collide"] = False
                    # register time of collision
                    player["last_col"] = timeit.default_timer()
            # ... or is object a coin?
            elif object.name.startswith("Coin"):
                player["coins"] += 1
                # play collecting sound with the aud module
                aud.device().play(player["coin_sound"])
                # remove the coin from the scene
                object.endObject()

    # player hasn't got lives?
    if player["lives"] <= 0:
        print("lost")
        # remove player from scene
        player.endObject()
        # stop game
        bge.logic.endGame()
    # player got all coins?
    if player["coins"] >= 10:
        print("Win")
        bge.logic.endGame()
    # player can collide again?
    if not player["can_collide"]:
        if (timeit.default_timer() - player["last_col"]) >= 1:
            player["can_collide"] = True

    # move player
    # keyboard events
    k_events = bge.logic.KX_INPUT_ACTIVE
    # up arrow pressed?
    if keyboard.events[bge.events.UPARROWKEY] == k_events:
        # move player forwards on its local y axis
        player.applyMovement((0, 0, .2), True)
    # down arrow pressed
    if keyboard.events[bge.events.DOWNARROWKEY] == k_events:
        # move player backwards on its local y axis
        player.applyMovement((0, 0, -.2), True)
    # left arrow pressed
    if keyboard.events[bge.events.LEFTARROWKEY] == k_events:
        # rotate to the left
        player.applyRotation((0, 0, .05))
    # right arrow pressed
    if keyboard.events[bge.events.RIGHTARROWKEY] == k_events:
        # rotate to the right
        player.applyRotation((0, 0, -.05))
    # Set the text
    text.text = "Lives: {}; Coins: {}".format(player["lives"], player["coins"])


def start(player):
    """Setup the player"""
    player["lives"] = 3
    player["coins"] = 0
    player["can_collide"] = True
    # sound with the aud module
    # coin collect sound
    path = bge.logic.expandPath("//snd/coin.wav")
    player["coin_sound"] = aud.Factory.file(path)
    # enemy hit sound
    path = bge.logic.expandPath("//snd/enemy.wav")
    player["enemy_sound"] = aud.Factory.file(path)


main()

And the Script for our Enemys:

#! bpy
import bge
from random import randint


def main():
    """Contains all changes"""
    # get scene
    scene = bge.logic.getCurrentScene()
    # get contoller
    con = bge.logic.getCurrentController()
    # get player
    enemy = con.owner

    # check, if enemy is outside the field
    if abs(enemy.position[0]) >= 20 or abs(enemy.position[1]) >= 20:
        # reverse direction
        enemy.applyRotation((0, 0, 180))
    # change direction in ca. 1% of the calls
    if randint(1, 100) == 1:
        # change direction
        enemy.applyRotation((0, 0, randint(1, 360)))
    # check for collisions
    for object in scene.objects:
        # does object collide
        # the distance is from origin to origin, so we subtract a bit
        if enemy.getDistanceTo(object) - 2 <= 0 and object != enemy:
            # Is object an enemy ...
            if object.name.startswith("Enemy"):
                # reverse direction
                enemy.applyRotation((0, 0, 180))
    # move
    enemy.applyMovement((0, 0, .15), True)


main()

The camera

Connecting the camera to the player: 1. Deselect all (»A« toggles selection) 2. Select the camera (with a right click) 3. Press shift while selecting the player, so you selected both and the player is active 4. Press »Ctrl« + »P« and click on »Object«

5. Select the camera again and enable »Slow Parent« in the Relations Extras
6. Set the Offset to »11.5«

More about Blender and the Game Enigne under Blender Game Engine – API